This dissertation critically examines the concept of "information" in an effort to understand the ways it participates in contemporary relations of power. Chapter 1 surveys the contemporary social, political, and economic conditions under which information operates today, and elaborates four "grammars" of information prominent in popular discourse. It also unpacks various assumptions implicit in these discourses, and explains the limitations of such popular accounts for theorizing information's role in various social formations. Chapter 2 performs an historical genealogy of information, tracing the concept's articulation in the American context, especially during the postwar period. This chapter discusses the work of Claude Shannon and Norbert Wiener, who formalized and mathematized the notion of information during this time, their reasons for and aims in doing so, and these theories' implications for conceptualizing information today. Chapter 3 builds on this analysis in order to pinpoint the particular problematic an historical account of information discloses: namely, that of "agency." This chapter traces this problematic's motivating influence through writing in first- and second-wave cybernetics. It demonstrates that critical social theory's current preoccupation with nonhumanistic theories of agency has conceptual roots in this writing, and offers a schematic for assessing accounts of agency that problematize accounts of the phenomenon inherited from the Enlightenment. Chapter 4 offers a "cartography" of contemporary theories of nonhumanistic agency in order to concretely connect these accounts with their forebearers in cybernetics and information theory; it then re-situates Shannonian and Wienerian theories of information in relation to this cartography. Chapter 5 concludes the dissertation by returning to information's popular articulations. It explains how a "mixed semiotic" approach to information and information technologies might enhance critical discussions of information politics, and attends specifically to the ways in which various figures of agency shape accounts of these politics.